public R2Ranking<S> computeRanking(List<S> population) {
for (S solution : population) {
solution.setAttribute(getAttributeIdentifier(), new R2SolutionData());
}
for (int i = 0; i < this.utilityFunctions.getSize(); i++) {
for (S solution : population) {
R2SolutionData solutionData = this.getAttribute(solution);
solutionData.alpha = this.utilityFunctions.evaluate(solution, i);
if (solutionData.alpha < solutionData.utility) solutionData.utility = solutionData.alpha;
}
Collections.sort(
population,
new Comparator<S>() {
@Override
public int compare(S o1, S o2) {
R2RankingAttribute<S> attribute = new R2RankingAttribute<>();
R2SolutionData data1 = (R2SolutionData) attribute.getAttribute(o1);
R2SolutionData data2 = (R2SolutionData) attribute.getAttribute(o2);
if (data1.alpha < data2.alpha) return -1;
else if (data1.alpha > data2.alpha) return 1;
else return 0;
}
});
int rank = 1;
for (S p : population) {
R2SolutionData r2Data = this.getAttribute(p);
if (rank < r2Data.rank) {
r2Data.rank = rank;
numberOfRanks = Math.max(numberOfRanks, rank);
}
rank = rank + 1;
}
}
Map<Integer, List<S>> fronts = new TreeMap<>(); // sorted on key
for (S solution : population) {
R2SolutionData r2Data = this.getAttribute(solution);
if (fronts.get(r2Data.rank) == null) fronts.put(r2Data.rank, new LinkedList<S>());
fronts.get(r2Data.rank).add(solution);
}
this.rankedSubpopulations = new ArrayList<>(fronts.size());
Iterator<Integer> iterator = fronts.keySet().iterator();
while (iterator.hasNext()) this.rankedSubpopulations.add(fronts.get(iterator.next()));
return this;
}
